Data Transfer Job Metrics

- Create `lib/galaxy/jobs/metrics/instruments/pulsar_transfer.py` following pattern of other classes, ensure type if `pulsar_transfer`.
- Read `self._instrument_file_path('preprocess')` in overridden `job_properties` method if it exists and return a metrics for it.
- In Pulsar's `preprocess` job manager file just write out the file `__preprocess_pulsar_transfer_preprocess` with whatever metrics you want in whatever format you want to read it in in `job_properties`.
- Postprocess is much harder I guess, good luck - you need to make sure that file gets back to Galaxy's working directory somehow (insert an action of some sort I guess)

The docker metrics plugin not yet in core if it helps (https://github.com/jmchilton/galaxy-central/commit/a24487bb36b32843c26657d45a6e685cff61bd49).